This invention relates to filter devices for removing organic contaminants from water either in the home or on a larger scale in a plant operated by industry or by a utility.
The problem of organic contaminants in domestic water supplies is well recognized at the present time. Some of these contaminants are quite dangerous although they may be present in drinking water in only a minute amount. It will be appreciated that it is difficult for authorities and scientists to determine the long-term harmful effects, if any, of these contaminants on human beings, particularily in view of the fact that there are a wide variety of such materials and the particular contaminants in any given drinking supply can vary from one community to another.
In an article entitled "Water Filters" published in Consumer Reports, February 1983, a number of existing water filtration systems and devices are described. It is recognized in this article that the known filters can help improve the taste or smell of the drinking water but not all are effective at controlling more dangerous contaminants. According to the same article more than 700 organic chemicals have been identified in drinking water and some of them are suspected cancer-causing agents.
Activated-carbon water filters are widely used to clean up water in bottling plants. On a more modest scale, carbon filters are used in the home to filter tap water. Some domestic water filters are attached to the faucet of the sink while others are installed in the cold-water line which may lead to a faucet.
Filters using carbon only may be unable to remove some dangerous organic compounds that are present in drinking water or drinking supplies. As an example of contaminants that exist in drinking water, the following list of organic compounds and the quantity thereof was published in Homemakers magazine in March 1983. The list was compiled by the organization known as Pollution Probe and it is based on a sample of water from Lake Ontario taken at a Toronto, Ontario location.
______________________________________ ORGANIC COMPOUNDS (parts per billion) ______________________________________ Aromatic Hydrocarbons Benzene .33 ppb Toluene .10 ppb Ethylbenzene Trace O--Xylene Trace M--Xylene Trace P--Xylene Trace Pesticides BHC .008 ppb Lindane .003 ppb DDE .002 ppb Dieldrin .001 ppb PCBs .001 ppb Trihalomethanes Chloroform 5.9 ppb Bromodichloromethane 7.5 ppb Chlorodibromomethane 1.8 ppb ______________________________________
Filters that employ filter materials other than or in addition to activated carbon are known. For example U.S. Pat. No. 4,305,826 issued Dec. 15, 1981 to Moses describes and illustrates a multi-layered filter for softening and filtering water. The first layer comprises particles of activated carbon, the second layer consists of beads of an organic ion cation exchange resin, the third layer is made up of granules of sodium aluminum silicate, and the fourth layer consists of filter sand. The layers are arranged vertically in a tank. The second and third layers of this filter act to soften the water. In addition the zeolite granuals in the third layer according to the patent will filter out most particles in the water whose size is greater than 20 microns.
Earlier U.S. Pat. No. 3,266,973 issued Aug. 16, 1966 to Richard P. Crowley describes a method of preparing paper stock which has an affinity for particular materials. During the manufacturing process finely divided zeolite crystaline molecular sieve particles are added to the pulp which is then formed into a sheet and dried. The product described in the patent can be used as filter paper capable of removing particles, gases and the like of a particular size and dimension from a fluid stream. In one embodiment the molecular sieve particles are employed in combination with water insoluble ion exchange resins to incorporate a combination of ion exchange and adsorbent properties into the fibrous material.
It is an object of the present invention to provide a filter device having at least three different filtering materials, which device is able to remove a wide range of organic materials from water.
It is a further object of the invention to provide a filter device that is easy to construct and that can be produced at a relatively low cost.
Devices constructed in accordance with the invention can be developed and designed for home or domestic use or for use by industry or utilities. Because the purchase cost of the domestic device is reasonably low, the homemaker need not regenerate the filter materials although this could be done with a large filter system such as one that might be used by a commercial operation or a utility.